In operation of a wellbore, it is a known practice to provide one or more fixed sensors inside the cement lining for acquiring data related to conditions in and characteristics of ground formations surrounding the wellbore. In order to enable fluid connection between the surrounding formation and a fixed sensor internal of the cement lining, it is known to perforate the cement lining after the cement has set, for example using small explosive charges.
An aim of the present invention is to provide an alternative and improved method of providing fluid pressure communication between the external formation and a fixed sensor inside the lining.